This invention relates to an apparatus for storing, draining, and dispensing beads which are stored and supplied in a liquid medium. The dispensing apparatus allows the beads to be dispensed essentially in the absence of the liquid medium.
Immunoassays employing beads are well known and have been extensively commercialized. The beads are generally used as solid phase supports for antigens or polyclonal or monoclonal antibodies, which may be covalently linked to and/or adsorbed onto the beads.
Various devices have been commercialized for dispensing beads which are supplied dry, for example, bead dispensers supplied by Abbott Laboratories, Litton Bionetics, Hybritech Inc. and Ventrex Laboratories, Inc. Typically, these dispensers are equipped with screw threads and are used by removing the cover of the bead jar and replacing it with the bead dispenser. In addition, U.S. Pat. No. 3,888,113 describes a reagent tube and stopper assembly for dispensing dry beads. U.S. Pat. No. 3,932,141 describes a receptacle tray apparatus for immunoassays with a plurality of wells. U.S. Pat. No. 4,101,284 discloses an apparatus for dispensing dry beads into any multi-well container, and U.S. Pat. No. 4,415,098 discloses a bead dispenser for gravity feed dispensing beads in dry form. Other patents such as, e.g., U.S. Pat. No. 2,886,208 disclose dispensers for dry items such as pills, tablets, pellets, etc.
Reasons such as stability, however, do not permit all beads to be supplied in dry form. Abbott Laboratories and Beckman Instruments Inc. supply wet beads in an apparatus equipped with a basket to hold the beads. For wet beads the usual instruction by the manufacturer is to drain the beads and then to use forceps or an aspiration device to dispense the beads into reaction tubes. Alternatively, beads can be added with forceps to a device such as the Beckman Immunoassay Processor and then simultaneously added to the reaction tubes.
Use of forceps or aspiration to dispense the beads is undesirable from several points of view: it is laborious, time-consuming and subject to error (dropping of the beads).
It is known that a basket can be used to drain items (see, e.g., U.S. Pat. No. Des. 249,924 for a frying pan). Furthermore, U.S. Pat. No. 4,162,875 describes a cabinet having holes in its side and bottom which will allow for draining materials held in the cabinet. The cabinet can fit inside a second receptacle. Also, U.S. Pat. No. 4,179,040 and the Tupperware catalog (1984), p. 30 describe a container having an inner insert which can be removed to drain the items held in the insert.